Process of separating orthotoluenesulfochlorid.



UNITED STATES PATENT OFFICE,

ALBERT BAUR, OF MULHOUSE, GERMANY, ASSIGNOR TO FABRIQUES DE PRODUITS OHIMIQUES DE THANN & DE MULHOUSE, OF TIIANN,

GERMANY.

PROCESS OF SEPAR-ATING QRTHOTOLUENESULFOCHLORID.

SPECIFIQATION forming part of Letters Eatent No. 692,598, dated February 4, 190523.

Application filed July 9, 1901. Serial No. 67,577. (No specimens.)

To It whom it may concern:

Be it known that I, ALBERT BAUR, a citizen of the Swiss Republic, residing at Mill-- house, Germany, have invented certain new and usefulImprovements in the Manufacture of Orthotoluenesulfochlorid, the Parent Material of Saccharin, of which the following is a clear and complete specification.

It is well known that by the action of sulfonic acid on toluene a mixture of ortho and para toluenesulfonic acid is formed. From this mixture the. para acidmay be separated according to Dr. Langes German Patent, No. 57,391, of September 23, 1890, a patent which is now void, by addition of a small quantity of water or ice. The mother-liquors contain a very small quantityof para acid, all the ortho acid, and the sulfuric acid used in excess of the theoretical quantity. By treatment with lime, filtration of the sulfate of lime, transformation of the lime sulfonate in the corresponding sodium salt, evaporation of the latter to dryness, and further treatment with pentachlorid of phosphorus the orthotoluenesulfochlorid may be obtained. This process is very expensive, and the orthosulfochlorid thus obtained is not absolutely pure. I have considerably improved the said process and have made it to an industrial one by two new and useful reactions, viz: First,I have first succeeded in separating the orthotoluenesulfonic mother-liquors in a perfectly pure state by adding to them a further quantity of water and allowing the liquor thus obtained to stand for a certain and rather long time at a low temperature; second, I secondly transform the orthotoluenesulfonic acid thus obtained in a salt, preferably the magnesium salt, and I act on this in an absolutely dry state with chlorosulfonic acid (SO HO1) and transform it by this way in orthotoluenesulfochlorid, which is a quite new reaction hitherto unknown.

The following example may be given as an illustration of my invention: To; four hundred kilos of sulfuric acid of 66 Baum I add,

' hundred and fifty kilos of fuming sulfuric acid containingtwenty-five percent. ofSO,,,and by coolingI maintain the temperature of the mixture at about 14 to 16 centigrade. having allowed theliquid to stand fora certain time I add slowlyabout one hundred and forty kilos of coldwateror ice, thetemperature being kept always under 20 centigrade. The paratoluenesulfonic acid is then separated in a crystalline state and cabe easily filtered. It may be hydrolized with dilute sulfuric acid separated from the orthotoluenesulfonic acid in the way wl1i ch.will be described afterward, and the toluene thus regenerated can be used for a furthersulfonation. In orderto isolate the orthotoluenesulfonic acid, I add to the liquor filtered from the paratoluenesnlfonic acid about one hundred and forty kilos of water, and Iallow it to stand for at least fortyeight hours at a low tem perature 5 below zero, or about so. The orthotoluenesulfonic acid then separates out in voluminous crystals,

which are filtered. The mother-liquors, which contain a little para and ortho sulfo acid of toluene and the excess of sulfuric acid, may be used for the hydrolysis of the above-mentioned paratoluenesulfonic acid,and the more dilute sulfuric acid thus resulting can be utilized for the manufacture of superphosphate or in anyother convenient manner.

The orthotoluenesulfonic acid retains a certain amount of sulfuric acid. In order to eliminate the latter, this ortho acid is dissolved in water and heated with the required quantity of lime,which combines with the sulfuric acid, forming insoluble'sulfate of lime. The solution obtained after filtering contains now the pure orthotoluenesulfonic acid. It is saturated with carbonate of magnesia, evaporated to dryness,and the magnesium salt heated at 110 to 120 centigrade. In order tov After (SO HOI) while always stirring and cooling outside, so that the temperature does not exceed 15 to 18 centigrade. Afterafewhours the reaction is finished. The mixture is poured on about one thousand kilos of ice I00 and the pure orthotoluenesulfochlorid separated from the aqueous liquid.

What I claim is 1. An improvement in the manufacture of orthotoluenesulfochlorid, which consists in separating pure orthotoluenesulfonic acid from a solution of the same in sulfuric acid by addition of a small quantity of water and action of a low temperature.

2. An improvement in the manufacture of orthotoluenesulfochlorid, which consists in acting with chlorosulfonic acid (S0 01) on a salt of orthotolnenesulfonic acid, at a temperature not exceeding 15 to 18 centigrade.

3. An improvement in the manufacture of orthotoluenesulfochlorid which consists in acting with chlorosulfonic acid (S0 01) on the magnesium salt of orthotoluenesulfonic acid at a temperature not exceeding 15 to 18 centigrade.

ALBERT BAUR. Witnesses:

GEO. G-IFFORD, AMAND BITTER, 

